WASHINGTON – Two federal agencies are being faulted for not coordinating their efforts against border gunrunners, a failure one lawmaker says made it easier for Mexican drug cartels to smuggle illegal weapons from the United States.

The Government Accountability Office criticized Immigration and Customs Enforcement and the Bureau of Alcohol, Tobacco, Firearms and Explosives for not working together to stop the flow of guns into Mexico.

In testimony prepared for a House subcommittee hearing Thursday, the GAO noted that the two agencies only recently stepped up their coordination with each other and with their Mexican counterparts to stop gunrunning along the border.

Rep. Eliot Engel, who chairs the subcommittee, said there should have been an anti-gunrunning strategy in place since October 2007, when the U.S. and Mexico agreed to the joint cartel-fighting Merida initiative.

“It is mind-boggling that for a year and a half, we have had no interagency strategy to address this major problem, but instead have relied on uncoordinated efforts by a variety of agencies,” Engel, D-N.Y., said in a statement issued ahead of Thursday’s hearing.

Engel said the firearms flowing illegally from the U.S. into Mexico have made the drug cartels’ jobs easier.

Citing ATF data, investigator Jess T. Ford said that over the past three years, more than 90 percent of the firearms traced after being seized in Mexico have come from the U.S. The figure is slightly less over a five-year period.

“While it is impossible to know how many firearms are illegally trafficked into Mexico in a given year, over 20,000, or around 87 percent, of firearms seized by Mexican authorities and traced over the past five years originated in the United States,” the GAO’s Ford said in testimony prepared for Thursday’s hearing.

The GAO is the investigative arm of Congress.

In a draft of the GAO report, investigators cited several examples of miscommunication between ICE and ATF, including:

During one operation, an ICE agent unknowingly covertly kept watch on the activities of an undercover ATF agent who was investigating a suspected trafficker.

ATF did not tell ICE about a covert operation where ATF agents delivered weapons across the border in an attempt to ferret out the Mexican organizations receiving illegal arms. ATF should have notified ICE about the controlled attempt to export weapons illegally, the GAO said. Lack of coordination raised the chances that the weapons could end up in the wrong hands.

In some cases, ICE and ATF refused to give each other required documentation for investigations.

The two agencies were working under a 1978 agreement about dual investigations, which the GAO cited as a major obstacle to coordination. An updated agreement to address the coordination problem is in the works, the report said.